Current HIV-1 therapy suffers from inadequate viral load suppression due to poor compliance, resistance, and interactions with other drugs and can lead to spread of drug-resistant strains. The current drug cocktails need to include inhibitors of viral components that are likely to slow resistance development. One such target is the HIV-1 capsid, an essential viral protein, where mutations are lethal or lead to production of non-infectious viral particles. Discovery of compounds that affect the assembly of structural proteins is challenging due to lack of a biochemical assay that can be adopted for high throughput screening of large compound libraries. We have recently reported an inhibitor of capsid assembly that reduced viral infectivity by ca. 95%. Cap-1 (ACH-1033940) was identified by combining the Computational Chemistry, NMR, and Virology efforts. Phase I of this proposal includes identification of a potent capsid assembly inhibitor (EC50 <10 mu/M, therapeutic index >10) as well as discovery of additional potent and drug like capsid ligands. The Phase I goal will be accomplished using a dual approach of rationally designing and synthesizing focused libraries of ACH-0133940 analogs and Virtual Screening of proprietary and commercial compound libraries to identify novel capsid ligands. The potential ligands will be screened for capsid binding by NMR and for inhibition of HIV by in vitro antiviral assays. Resistance induction studies will be carried out to confirm that inhibition of HIV infectivity is due to the inhibition of capsid assembly. Phase II of the project will entail further lead optimization and identification of development candidate(s).